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		Referer 
	
	
		
			Referer
		
	
	is a common misspelling of the word "referrer"; so common, in fact, that it made it into the official specification of 
	HTTP 
	- the communication 
	protocol 
	of the 
	world wide web 
	. When visiting a 
	webpage 
	, the 
	
		referer 
	
	(sic) or 
	
		referring page 
	
	is the 
	URL 
	of the previous webpage from which a 
	link 
	was followed. More generally, it is the URL of a previous item which led to this request - the referer for an image, for example, is generally the 
	HTML 
	page on which it is to be displayed. The referer is part of the HTTP request sent by the 
	browser program 
	to the 
	web server 
	. 
 
Many web sites log referers as part of their attempt to track their users. Most 
web log analysis software 
can process this information. As referer information can violate 
privacy 
, some browsers have the option of disabling this functionality. Some 
proxy 
and 
firewall 
software will also block referers, to avoid leaking the location of non-public websites. This can in turn cause problems: some servers block parts of their site to browsers that don't send the right referer information, in an attempt to prevent 
deep linking 
or unauthorised use of images (
bandwidth theft 
). 
 
Recently many blogs have started publishing referer information in order to link back to people who are linking to them, and hence broaden the conversation. This has led, in turn, to the rise of 
referer spam 
. 
 
Reference 
	
		RFC 2616: Hypertext Transfer Protocol -- HTTP/1.1 
 
Retrieved from http://en.wikipedia.org/wiki/Referer 
 
Reprinted from Wikipedia, The Free-Content Encyclopedia under the GNU Free Documentation License.  
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